I couldn't say with any certainty, Michael, that a tune such as that - with all the music-hall and variety stuff that went before - was 100% copper-bottomed original. All I can say is I really haven't come across anything that appears to be an ancestor of it. My best guess would be that it was inspired by the tune used to back Wilson, Keppel & Betty, which was (I think) taken from the "Ballet égyptien, Op. 12 (1875" by Alexandre Luigini.